The contract is to provide support for the performance of double antibody radioimmunoassays for human and mouse immunoglobulins, ELISA assays for soluble interleukin2 receptors and antimouse immunoglobulin antibodies, and to perform passive hemagglutinnization assays and enzymelinked immunoabsorbent ELISA assays for serum antibodies to protein and polysaccharide antigens. These radioimmunoassays and ELISAs are integral parts of major studies of the Metabolism Branch, NCI being carried out by the Project Officer, Dr. Thomas A. Waldmann and by five other senior investigators on the Metabolism Branch; Drs. R. Michael Blaese, David Nelson, Andrew Muchmore, Ajay Bakhshi and Jay Berzofsky. In addition, the procedures are being used in clinical care protocols for patients with malignant and immunodeficiency diseases admitted to the 3B Metabolism Branch ward in the Clinical Center.